Illuminated sign and sign plate therefor

ABSTRACT

A sign plate for an edge-iluminated sign including a transparent sheet with a front face, a rear face and a transparent edge that connects the front face to the rear face, wherein the transparent edge is positioned to receive light from a light source for transmission along the transparent sheet. The sign plate further includes a front image layer disposed on a front face of the transparent sheet, wherein the front image layer has a reflective surface. A rear image layer is disposed on a rear face of the transparent sheet substantially in registry with the front image layer, wherein the front image layer and the rear image layer are positioned so that the light within the transparent sheet is reflected from the reflective surface onto the rear image layer thereby to enhance illumination of the rear image layer. The sign plate has a structure such that a portion of the light within the transparent sheet forms an image of a halo or aura of light surrounding of the rear image layer.

Applicant claims, under 35 U.S.C. § 119, the benefit of priority of thefiling date of Sep. 8, 1995, of United Kingdom Application No.9518397.6, filed on the aforementioned date, the entire contents ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an illuminated sign and to a sign platefor an illuminated sign.

2. Description of the Related Art

Edge-illuminated signs are known in which a transparent plastics sheetis illuminated by a light source disposed along one edge thereof so thatlight passes through the sheet material in a direction along the planeof the sheet. An image to be displayed is formed on one of the faces ofthe sheet whereby the light contrast between the image and the remainderof the sheet increases the visual impact of the image to a personviewing the sign. A typical known edge-illuminated sign is illustratedin FIG. 1.

Referring to FIG. 1, a transparent plastic sheet 2, typically of acrylicplastic material, which is rectangular in shape has one edge 4 thereofreceived in a lamp housing 6 in which an elongate bulb 7, typically afluorescent bulb, and electrical fittings 9 therefor are received, thebulb extending substantially along the length of the edge 4. In use, anend cap 8 is fitted over each end 10 of the lamp housing 6. In FIG. 1,which is a partially exploded view, one end cap 8 is shown in itsremoved configuration and the bulb and electrical fittings 9 arepartially removed so that the edge 4 of the sheet 2 is readily visible.The sheet 2 is provided either on its frontmost face 12 or its rearmostface 14, the direction being with respect to the intended position of aviewer of the sign, with an image 16. The image 16 may be formed byengraving the surface of the sheet 2 or by printing a partiallytransmissive printed ink layer on the surface of the sheet, for exampleby screen printing. When the bulb 7 is illuminated, light emitted fromthe bulb 7 passes along the sheet 2 from the edge 4 and is internallyreflected at the sheet/air interfaces. When the image 16 is a engraved,light passing along the sheet 2 is reflected and refracted at theengraved edges thereby illuminating the edge of the image 16. When theimage 16 is printed, the internally reflected light is incident on therear surface of the image 16 and is partially transmitted to the frontsurface of the image 16 thereby to provide an illuminated image.

When the image is engraved this increases the cost and complexity ofmanufacture of the illuminated sign. When the image is printed, thedegree of contrast of the image is not particularly high and so the signis not particularly effective in ambient conditions of high lightintensity. Furthermore, for both prior arrangements the nature of theimages which can be conveyed by the signs is relatively limited.

U.S. Pat. No. 5,009,019 and WO-A-93/07605 are both in the name of thepresent inventor and relate to sign plates for illuminated signs. Bothof these prior specifications disclose a sign plate for an illuminatedsign which is intended to be illuminated by a light source disposedbehind a rearmost face of the sign plate.

An aim of the present invention is to provide an improvededge-illuminated sign. It is a further aim of the present invention toprovide an edge-illuminated sign which can be manufacturedcost-effectively and can provide enhanced illumination of the image ascompared to known edge-illuminated signs. It is a further aim of thepresent invention to provide an edge-illuminated sign which enables awide variety of images to be displayed.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an illuminated signcomprising a light source, a transparent sheet having one edge thereofwhich one edge is assembled adjacent the light source for receivinglight therefrom which, in use, is transmitted along the transparentsheet, a front image layer which is disposed on a front face of thetransparent sheet and has a rearwardly-directed reflective surface and arear image layer which is disposed on a rear face of the transparentsheet substantially in registry with the front image layer whereby, inuse, light is reflected from the reflective surface onto the rear imagelayer thereby to enhance the illumination of the rear image layer.

The present invention further provides a sign plate for anedge-illuminated sign, the sign plate comprising a transparent sheethaving one transparent edge thereof for receiving from a light sourcelight for transmission along the transparent sheet, a front image layerwhich is disposed on a front face of the transparent sheet and has arearwardly-directed reflective surface and a rear image layer which isdisposed on a rear face of the transparent sheet substantially inregistry with the front image layer whereby, in use, light is reflectedfrom the reflective surface onto the rear image layer thereby to enhancethe illumination of the rear image layer.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a partially exploded perspective view of a knownedge-illuminated sign;

FIG. 2 is a perspective view of an edge-illuminated sign in accordancewith a first embodiment of the present invention;

FIG. 3 is a cross-section on line A--A of the edge-illuminated signillustrated in FIG. 2;

FIGS. 4 & 5 are schematic views similar to that of FIG. 3 illustratingthe mechanism of the transmission of light along and out of thetransparent plastic sheet of the sign illustrated in FIG. 2; and

FIG. 6 is a cross-section through an edge-illuminated sign in accordancewith a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring to FIGS. 2 and 3, there is shown an edge-illuminated sign,designated generally as 20, in accordance with a first embodiment of thepresent invention. The sign 20 comprises a lamp housing 22 in the formof a cylindrical tube. At opposed ends of the lamp housing 22 areprovided electrical fittings 24 for a fluorescent bulb 26 which extendsalong the length of the lamp housing 22. The lamp housing 22 is providedin its lower surface with an axially directed elongate slot 28 whichreceives the uppermost edge 30 of a transparent plastic sheet 32 whichis supported by and depends downwardly from the lamp housing 22. In theillustrated embodiment, the transparent plastic sheet 32 is rectangularin shape, having two upright side edges 34,36 and a lowermost edge 38.

As is shown clearly in FIG. 3, the lowermost edge 38 is inclined to theplane of the sheet 32 with the internal face of the edge 38 facingtowards the front face 40 and away from the rear face 42 of the sheet32. The inclined edge 38 is preferably at an angle of less than about45° to a line perpendicular to the sheet 32 so that light is reflectedback from the edge 38 into the sheet 32 at a relatively low angle so asto subsequently be internally reflected back up through the sheet 32with minimal loss of light intensity. In an alternative arrangement, theinclined edge 38 faces towards the rear face 42 rather than the frontface 40. The front face 40 of the sheet 32 is coated with a front imagelayer 44 which is patterned in the shape of an image to be displayed bythe sign 20 (in the illustrated embodiment, the letter A which is shownmerely by way of example). The rear face 42 of the sheet 32 is coatedwith a correspondingly shaped rear image layer 46 which is disposed inregistry with the front image layer 44. In the illustrated embodiment,the width of the rear image layer 46 (in the plane of the layer 46) isdimensionally larger than that of the front image layer 44 whereby therear image layer 46 defines, in regions such as regions 48,50,52,54illustrated in FIG. 3, a peripheral margin 56 surrounding andhighlighting the image conveyed by the front image layer 44. The frontimage layer 44 has a rearwardly directed surface 58 which is reflective.Preferably, the front image layer 44 comprises a self-adhesive plastic(e.g. vinyl) film which has an underlying self-adhesive reflectivesurface 58. The plastic film may be fluorescent and translucent. Thefront image layer 44 or its reflective surface may be provided by ametallic and/or brightly colored (e.g. white) paint layer or by ametallised or brightly colored coating on or in the plastic film. Thepaint layer 44 may be fluorescent and at least partially translucent.The front surface 60 of such a front image layer 44 may have beenprovided with any suitable color, pattern or image, either by such acolour, pattern or image being present in the film or having beenapplied thereto. The front image layer 44 may alternatively comprise aprinted film of any desired color or colors. The rear image layer 46comprises a layer of fluorescent material of any desired color orcombination of colors which preferably has been printed, for example byscreen printing, onto the rear face 42 of the sheet 32. Preferably, therear image layer 46 is partially transmissive for visible light. In analternative embodiment, the rear image layer may comprise aself-adhesive plastic (e.g. vinyl) film which is preferably fluorescentand translucent. The front and rear image layers may incorporatephosphorescent materials.

A backing sheet 62 is mounted behind and parallel with the sheet 32. Thebacking sheet 62 has a front face 64 which is preferably spaced slightlyfrom the rear face 42 of the sheet 32. The backing sheet 62 ispreferably comprises a substantially opaque plastic sheet having adesired color and/or a fluorescent coating. The backing sheet 62 mayhave any desired image or pattern or the front face 64 or the rear face66 thereof when the backing sheet 62 is translucent. Alternatively, thebacking sheet 62 may comprise a transparent plastic sheet having asubstantially opaque coating on the front face 64. The lamp housing 22is configured to provide a mount 68 for the upper edge 70 of the backingsheet 62. A bottom mount 72 is provided along the respective adjacentbottom edges 38,74 of the transparent sheet 32 and the backing sheet 74.Preferably, the inner surface 76 of the bottom mount 72 which abuts theinclined bottom edge 38 of the transparent sheet 32 is reflective. Asshown schematically in FIG. 3, clamping devices 78,80 may be providedfor holding together the assembly of the transparent sheet 32 and thebacking sheet 62.

The operation of the edge-illuminated sign 20 will now be described withreference to FIGS. 4 and 5.

In use, the fluorescent bulb 26 is illuminated and as shown in FIG. 4,light beams, such as light beam 82, which are not parallel to the planeof transparent sheet 32 are transmitted through the plane of the sheet32 by internal reflection at alternatively the inner and outer faces40,42 of the transparent sheet 32. It will be seen that since in theillustrated embodiment the only layers which are formed on the front andrear faces 40,42 of the transparent sheet 32 are the front and rearimage layers 44,46, there is an enhanced degree of internal reflectionof light being transmitted along the sheet 32, the light beinginternally reflected at the sheet/air interfaces. If additional layerswere present intimately covering the sheet faces, then the degree ofinternal reflection would be reduced because light would be absorbedinto these additional layers, thereby reducing correspondingly the levelof illumination of the desired image. For this reason, the backing sheet62 may be adjacent to, but not adhered or otherwise intimatelyconnected, bonded or adhered to the transparent sheet because this wouldreduce the total amount of light internally reflected in the transparentsheet.

As shown in FIG. 5, any light beam 84 which is parallel to the plane ofthe transparent sheet 32 is transmitted down the entire length of thesheet 32 and subsequently reflected by internal reflection at theinclined face 38, or reflected by reflection at the reflecting face 76of the lower mount 72, and the reflected beam 86 is transmitted back upthe transparent sheet 32 and subsequently internally reflected at theinner and outer faces 40,42 of the transparent sheet 32. In this way,light from the bulb 26 is transmitted throughout the whole body of thetransparent sheet 32.

Light beams which are not parallel to the plane of the transmittingsheet 32 are reflected to a significant extent at the reflective surface58 of the front image layer 44. This reflected light (e.g. at arrow 88)is reflected to a significant extent back onto the fluorescent rearimage layer 46. This provides an enhanced illumination of thefluorescent rear image layer 46 so that the edges of the rear imagelayer 46 which are not directly covered by (i.e. are at least partiallyexposed by) the front image layer 44 appear very bright to a viewer ofthe sign (e.g. at arrow 90). This brightness is enhanced by thefluorescent effect of the rear image layer 46 which strongly emitsfluorescent radiation as a result of being illuminated by light from thebulb 26. The overall illumination effect to a viewer of the sign 20 is astrongly illuminated fluorescent annular border or highlight surroundingthe image defined by the front image layer 44. This provides anilluminated outline at least partially around indicia defined by thefront image layer.

The front image layer 44 may be substantially opaque or partiallytransmitting. If the front image layer 44 is partially transmitting,then as shown in FIG. 4 some light (e.g. at arrow 92) is reflected fromthe rear face 42 of the sheet 32 forwardly through the front image layer44 whereby the image defined by the front image layer 44 is partiallyilluminated.

The fluorescent layer 46 is partially transmitting and accordingly light(e.g. at arrow 94) passes rearwardly through the fluorescent layer 46and onto the backing sheet 62. Such light is reflected from the backingsheet 62 at its front face 64 (e.g. at arrow 94) and such reflectedlight is transmitted forwardly through the transparent sheet 32. Suchreflected light from the backing sheet 62 provides an image of a halo oraura of light surrounding the image defined by light reflected from thefluorescent rear image layer 46. The halo of light is illustrated inFIG. 1. The color of the halo of light is preferably the same as that ofthe fluorescent rear image layer 46. The color may be varied by applyingan additional colored layer to the back of the rear image layer or tothe front of the backing sheet. The lateral width of the halo may bevaried by altering the spacing between the transparent sheet 32 and thebacking sheet 62.

A further embodiment of illuminated sign 90 in accordance with thepresent invention is illustrated in FIG. 6 which is similar to theembodiment illustrated in FIGS. 2 to 5 except that the opaque backingsheet 62 is replaced by a transparent backing sheet 96 having areflecting coating 98 on its rear face 100. The reflecting coating 94comprises a self-adhesive plastic film 102 having a reflecting frontsurface 104. Alternatively, the reflecting coating 94 is a printedlayer. In a similar manner to that illustrated in and described withreference to FIGS. 4 and 5, a halo effect is provided around thefluorescent rear image layer 46 by light being reflected off thereflecting surface of the film 98 (e.g. at arrow 106). Since thereflecting film 102 is on the face 100 of the backing sheet 96 which isremote from the transparent sheet 32, there is no requirement for thebacking sheet 96 to be spaced in order to provide a visible halo effect.

It will be apparent to those skilled in the art that variousmodifications can be made to the illustrated embodiments within thescope of the invention. In the illustrated embodiments, the front imagelayer lies wholly within the lateral periphery of the rear image layerso that a peripheral highlight is defined by a border portion of therear image layer which surrounds the front image layer. In alternativeembodiments, although the rear image layer would generally be inregistry with the front image layer, the rear image layer may belaterally offset relative to the front image layer or may have smallerdimensions than the front image layer on one side thereof so as toprovide a highlight which is offset and does not extend all the wayaround the periphery of the front image layer. Thus the highlight mayappear as a highlighted "shadow" on one side of the image defined by thefront image layer. In a further embodiment, the front and rear imagelayers may be aligned and have the same size and shape. With thisembodiment a highlight or outline can be seen by a viewer looking at thesign at an angle.

In the embodiments of the invention, the front and rear image layers areseparated by a distance corresponding to the thickness of thetransparent sheet. When the front and rear image layers are illuminatedin the manner described hereinabove, the viewer is able to detect aspecial difference between the front and rear image layers. This createsa three dimensional effect whereby the front and rear image layersappear to be connected by an inclined edge, giving the overall indicia amassive and solid appearance. The thickness of the three dimensionalimage corresponds to the thickness of the transparent sheet. The shapeand angle of inclination of the inclined edge can be varied by alteringthe relative sizes and disposition of the front and rear image layers.For example, if the rear image layer is slightly larger in lateraldimension than the front image layer all around its periphery, then arelatively steep inclined edge will be apparent to a viewer of the signwhen the sign is illuminated.

The images to be conveyed may comprise alphanumeric characters or otherpictorial images. The front image layer may itself be printed orotherwise provided with images on its front surface.

Although the transparent sheet is illustrated as depending downwardlyfrom the lamp housing 22, in alternative configurations the lamp housingmay be provided beneath the transparent sheet and may constitute asupport stand for the entire sign. In addition, although the illustratedembodiments utilise a fluorescent bulb as the light source for theilluminated sign, any other suitable light source may be employed, forexample an incandescent bulb, a neon bulb, etc.

In alternative embodiments, a light reflective self-adhesive plasticlayer, for example white or silver in colour, is adhered over the edgeof the sheet which is remote from the light source in order to reflectlight back through the sheet. The mount along that edge may be squarerather than inclined, particularly for small dimension signs.

In accordance with the invention, the provision of a fluorescent layerat least partially surrounding the front image layer on the transparentsheet, together with the provision of a reflecting surface on the rearof that front image layer, provides real technical advantage as opposedto edge-illuminated signs in the prior art by forming an illuminatedimage having a relatively high intensity. This means that theedge-illuminated sign is clearly visible to a viewer even in relativelyhigh intensity ambient light and when the sign is intended to be seenfrom a substantial distance away. The sign of the present invention alsohas great flexibility in use by enabling a wide variety of visualeffects to be reproduced. For example different colours can be displayedwith or without fluorescent layers. An aura of one or more colors maywholly or partially surround the indicia. The color, size, shape andorientation of a highlight around the indicia may be selected asdesired. Printed or patterned images defining or surrounding the indiciamay be provided. The sign can be manufactured very cost effectively byusing known printing techniques and known techniques for applyingpatterned self-adhesive plastic films to rigid plastic sheets in therequired positions.

The provision of a light reflection device at the edge of the sheetwhich is away from the light source ensures that the amount of lightinternally reflected in the sheet to cause illumination of the indiciais substantially maximised. This not only increases the visibility ofthe sign but also provides even and uniform illumination of the indiciaon both sides thereof, i.e. on the sides which are near to and remotefrom the light source.

I claim:
 1. An illuminated sign comprising:a light source generatinglight along a first direction, a transparent sheet comprising a frontface, a rear face and an edge that connects said front face to said rearface, wherein said edge is positioned adjacent said light source forreceiving said light generated along said first direction so that saidlight is transmitted within said transparent sheet along said firstdirection, a front image layer disposed on a front face of saidtransparent sheet, wherein said front image layer comprises a reflectivesurface that faces a second direction perpendicular to said firstdirection; a rear image layer disposed on a rear face of saidtransparent sheet substantially in registry with said front image layer,wherein said front image layer and said rear image layer are positionedso that said light within said transparent sheet is reflected from saidreflective surface onto said rear image layer thereby to enhanceillumination of said rear image layer; and wherein a portion of saidlight within said transparent sheet forms an image of a halo or aura oflight surrounding said rear image layer.
 2. An illuminated signaccording to claim 1 wherein said front image layer comprises aself-adhesive plastic layer.
 3. An illuminated sign according to claim 1wherein said front image layer comprises a printed layer.
 4. Anilluminated sign according claim 1 wherein said front image layer ispartially transmissive.
 5. An illuminated sign according to claim 1wherein said rear image layer comprises a fluorescent layer.
 6. Anilluminated sign according to claim 5 wherein said fluorescent layercomprises a self-adhesive plastic layer.
 7. An illuminated signaccording to claim 5 wherein said fluorescent layer comprises a printedlayer.
 8. An illuminated sign according to claim 1 wherein said frontimage layer and said rear image layer are mutually shaped and orientedwhereby said front image layer at least partially overlaps said rearimage layer.
 9. An illuminated sign according to claim 8 wherein anannular peripheral portion of said rear image, layer surrounding saidfront image layer is exposed by said front image layer.
 10. Anilluminated sign according to claim 8 wherein said front image layer islaterally offset with respect to said rear image layer.
 11. Anilluminated sign according to claim 1 wherein said front and rear imagelayers are dimensioned and positioned with respect to each other so asto provide an illuminated outline at least partially around indiciadefined by said first image layer.
 12. An illuminated sign according toclaim 1 further comprising a backing sheet located rearwardly of saidrear face of said transparent sheet.
 13. An illuminated sign accordingto claim 12 wherein said backing sheet is opaque.
 14. An illuminatedsign according to claim 12 wherein said backing sheet comprises a secondtransparent sheet carrying an opaque layer.
 15. An illuminated signaccording to claim 14 wherein said opaque layer is disposed on a rearface of said second transparent sheet.
 16. An illuminated sign accordingto claim 12 wherein said front face of said backing sheet is spaced fromsaid rear face of said transparent sheet.
 17. An illuminated signaccording to claim 16 wherein said backing sheet is parallel to saidtransparent sheet.
 18. An illuminated sign according to claim 16 whereinthere is an empty space between said front face of the backing sheet andsaid rear face of said transparent sheet.
 19. An illuminated signaccording to claim 18 wherein said backing sheet overlaps a substantialportion of said rear face of said transparent sheet.
 20. An illuminatedsign according to claim 19 wherein said backing sheet is parallel tosaid transparent sheet.
 21. An illuminated sign according to claim 18wherein said backing sheet is parallel to said transparent sheet.
 22. Anilluminated sign according to claim 16 wherein said backing sheetoverlaps a substantial portion of said rear face of said transparentsheet.
 23. An illuminated sign according to claim 12 wherein the rearimage layer is partially transmissive whereby, in use, light transmittedtherethrough onto said backing sheet creates an illuminated aura aroundsaid rear image layer.
 24. An illuminated sign according to claim 1wherein a second edge of said transparent sheet which is opposite saidedge connecting said front face to said rear face to adapted to reflectlight incident upon said second edge back into the transparent sheet.25. An illuminated sign according to claim 24 wherein the second edge isinclined to a plane defined by said transparent sheet.
 26. Anilluminated sign according to claim 25 wherein said second edge isinclined at an angle of up to about to 45° to a line perpendicular tosaid plane defined by said transparent sheet.
 27. An illuminated signaccording to claim 24 further comprising a reflecting member whichcovers said second edge thereby to reflect light into said transparentsheet.
 28. An illuminated sign according to claim 27 wherein saidreflecting member comprises a mount for said transparent sheet and saidbacking sheet.